Land mine



2,857,842 LAND MINE Karl Olof Bertii Malm, Stockholm, Sweden ApplicationMarch 12, 1956, Serial No. 570,841 7 Claims. (Ci. 102-8) The presentinvention relates to an arrangement in land mines of the kind which areprovided with a detonator to be initiated by means of a percussiondevice and provided with a releasing device which is inoperative whenacted upon by pressure waves in the air but operable by being tiltedinto an inclined position when the mine is treaded upon or actuated by acar or the like. The invention is characterized chiefly by the fact thatthe releasing device is mounted in a spherical bearing in the mine insuch a way that the percussion device is brought into action by a mutualdisplacement of the spherical bearing surfaces.

The invention is illustrated on the accompanying drawings which in Figs.1 and 2 show two different em bodiments of the land mine in a verticalsection.

In the example shown in Fig. 1 the bursting charge 1 is provided in acalotte-shaped receptacle 2 which is open upwards and turnable in alldirections in a bowl 3 having a spherical bottom which forms thestationary part of the spherical bearing. The bowl 3 is provided with acylindrical flange 4 which together with the central part of the bowlforms the support of the mine when placed on the ground. The receptacle2 is provided with a central tube 5 into the upper end of which adetonator 6 is screwed which in the usual way is provided with abursting charge and an initiating charge arranged to be actuated upon bya percussion device. The device last mentioned consists in the exampleshown of a percussion pin 7 guided in a cylindrical piston 8 andnormally held in retracted position by balls 9 against the action of aspring 10. The lower pointed end of the piston 8 normally projects intoa recess 11 in the spherical surface of the bowl 3. The mine is closedby means of an elastic covering 12 of rubber or the like.

When the mine is treaded upon the pressure will act eccentrically on theupper surface of the mine or on the edge of the receptacle 2 so as tocause the latter to tilt over in its spherical bearing and take up aninclined position. The receptacle 2 will then act as a releasing devicefor the percussion device as the piston 8 is now pressed upwards in thetube 5 until the balls 9 are in level with a wider part of the tube 5when the balls are pressed out of their stopping positions so as torelease the percussion pin 7 which, by the action of the spring 10, isflung against the detonator thereby causing the charge to burst.

In the example shown in Fig. 2 the percussion pin is inserted in anelastic and resilient washer 13, a so-called Belleville washer, by meansof which the percussion pin is normally held against a ball 14 insertedin a hole in a central part 15 of the bottom of the receptacle 2', theball being at the same time kept in engagement with the central recessin the bowl 3. When the receptacle 2 is brought into an inclinedposition, the ball 14 is pressed upwards, thereby causing the percussionpin 7' by the spring action of the washer 13, to be carried over itsposition of equilibrium so as to operate the detonator.

The mine may be put on safe by screwing away the detonator 6. In orderto prevent unintentional bursting when the mine is placed on the groundthe mine is covered, before being laid out, with a lid 16 provided witha cylindrical flange 17 enclosing the mine whereby the releasing device18 locked. After the mine has been in this way made safe to handle thedetonator is inserted through the central opening of the lid 16 andscrewed States Patent 0 into place. The mine is then finally, the lid 16is removed.

The free space underneath the bowl 3' may, if required, be filled upwith a bursting charge. The receptacle 2' and the bowl 3' may be made ofany suitable substance. For the rest the mine is chiefly made ofnon-magnetic material with the exception of the percussion pin whichshould be of steel. Also the washer 13 may be made of non-magneticmaterial.

It will be evident that an evenly distributed pressure on the uppersurface of the mine will not cause a release of the percussion device.As a consequence, the mine cannot be actuated by pressure waves causedby charges bursting in the neighborhood.

What is claimed is:

1. A land mine comprising, in combination, a base member having an upperconcave spherical bearing surface, an operating member supported by saidbase member and having an upper tread surface and a lower convexspherical bearing surface concentric with and fitting the concavebearing surface of the base member, the operating member being mountedin the base member for free tilting movement in all directions, apercussion device mounted in one of said members, and means foractuating said percussion device upon tilting movement of the operatingmember relatively to said base member.

2. A land mine as defined in claim 1, wherein the operating memberdefines the container for. the charge of explosive.

3. A land mine as defined in claim 1, wherein the base member and theoperating member are joined together along their outer edges by anelastic covering.

4. A land mine as defined in claim 1, wherein the operating member islocked to the base member in nonoperating position by a lid having aflange covering the outer side surfaces of both of said members.

5. A land mine as defined in claim 1, wherein one of said bearingsurfaces is provided with a recess and said means for actuating thepercussion device comprises an actuating member engaging in said recessand being adapted to be released upon mutual displacement of the bearingsurfaces.

6. A land mine as defined in claim 5, wherein said recess is formed inthe bearing surface of the base member and the percussion device iscarried by a Belleville spring engaged by a ball seated in the recess inthe lower bearing surface.

7. A land mine comprising, in combination, a base member having an upperconcave spherical bearing surface formed with a recess, an operatingmember supported by said base member and having an upper tread surfaceand a lower convex spherical bearing surface concentric with and fittingthe concave bearing surface of the base member, the operating memberbeing mounted in the base member for free tilting movement in alldirections, a spring actuated percussion device disposed axially in theoperating member, and an actuating member movable coaxially with thepercussion device and engaging in said recess in the spherical surfaceof the base member for actuation upon mutual displacement of said twobearing surfaces.

placed on the ground and,

References Cited in the file of this patent UNITED STATES PATENTS2,488,547 Liljegren Nov. 22, 1949 2,514,401 Liljegren July 11, 1950FOREIGN PATENTS 315,825 Germany Nov. 13, 1919 239,129 Great BritainSept. 3, 1925 710,621 Germany Sept. 18, 1941 577,815 Great Britain June3, 1946

